A sudden brightening of the Sun's surface near sunspots, lasting from a few minutes to a few hours. Flares occur when magnetic energy built up in the solar atmosphere near a sunspot is suddenly released in a burst equivalent to ten million volcanic eruptions. Radiation - including radio waves, X rays, and gamma rays - and charged particles may strike the Earth following a solar flare, though most of the particles are deflected by Earth's magnetic field. A couple of days after flares have been observed, more auroras than usual can be seen on Earth. This is because energy stored in the magnetic field is released, and short-wave radiation affects the Earth's ionosphere.
The strongest flares occur just several times per year, while weaker flares are relatively common, with as many as a dozen a day during the Sun's most active periods. A bright solar flare is here captured by EIT.
